This study was conducted to a) determine the rates of mineral N accumulation in soil (Dark Red Latosol or Typic Haplustox, oxidic, isothermic) under greenhouse conditions when leaves of Mucuna aterrima (Piper and Tracy) Merr. were either surface placed or mixed with the soil, and b) determine the amount of N lost from the surface placed legume which is recovered in the soil as mineral N. After 178 days, the treatment where mucuna was incorporated had a net inorganic N accumulation 60% higher than the treatment with mucuna placed on the surface. After 178 days, only 55% of N applied as surface placed legume was found in the remaining undecomposed residue or as inorganic N in the soil. The data and literature suggest that part of this unrecovered N was lost by ammonia volatilization.